Surge muffler for air storage tank



Nov. 29, 1960 J. B. DEPMAN 2,962,110

SURGE MUFFLER FOR AIR STORAGE TANK Filed Aug. 9, 1957 I 2' COMPEESSQG IN VEN T OR.

United States Patent SURGE MUFFLER FOR AIR STORAGE TANK Joseph B. Depman, Birmingham, Mich., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed Aug. 9, 1957, Ser. No. 677,391

'6 Claims. (Cl. 181-436) This invention relates to air supply and storage for pneumatic vehicle. suspension and more particularly to means for reducing storage tank resonance resulting from surge characteristics in a compressor supplying said air.

Air suspension systems for vehicles quite generally employ single cylinder reciprocating piston type compressors as the source of compressed air. As a rule, compressed air generated by the compressor is conducted by a suitable conduit directly to an accumulator or high pressure storage tank which, in turn, communicates with the remainder of the suspension system to supply the dynamic requirements thereof.

For various reasons, among which are economy of production and minimum weight, high pressure storage tanks are preferably fabricated from relative thin sheet metal. Operational experience with air suspended vehicles employing such high pressure tanks disclosed a tendency of the latter to produce an objectionable ringing noise induced by inherent surge characteristics of the air compressor.

An object of the present invention is to provide means for eliminating high pressure storage tank resonance induced by surging or pulsing delivery of air thereto. t

Another object is to provide a compact surge mufiler for high pressure air storage tanks.

A further object is to provide a device of the stated character which is adapted to be positioned interiorly of the tank.

A still further object is to provide a surge muffler for an air accumulator which is formed as an integral part of an inlet fitting so as to permit maximum ease of assembly or disassembly.

Still a further object is to provide a muffler construction of the stated character having maximum compressor surge reducing capabilities with minimum flow restriction.

Yet a further object is to provide an air storage tank inlet fitting incorporating a mufiier of the stated character and means for initially charging the tank from a source other than the compressor.

These and other objects, advantages and features of the invention will become more fully apparent as reference is had to the accompanying specification and drawing.

The drawing illustrates a typical thin walled high pressure tank having a threaded inlet fitting connected thereto which incorporates a surge muffler and charging device according to the present invention.

In the drawing, the reference character 2 designates generally a thin walled hollow body adapted to receive and store compressed air derived from any conventional engine driven piston type compressor, not shown. It will be understood that the tank 2, as shown, is highly foreshortened, such tanks in practice being relatively long in comparison to their diameter. Extending through an aperture 4 formed in the upper side wall of the tank and brazed to the latter is a flanged fitting 6 having internal threads 8 extending partially through the internal bore 10 thereof. Threads 8 are adapted to receive the threaded inner end portion 12 of a fitting 14. Fitting 14 has central bore 16 extending through its horizontal length and at its opposite end 18 is provided with an internally threaded counterbore 20 which provides for fluid tight connection with the outlet side of a piston type compressor, previously referred to.

According to one feature of the invention, in order to reduce or eliminate the tendency of the tank 2 to resonate due to pulsing or surging delivery of air from the compressor, the inner end 12 of fitting 14 is formed with a counterbore 22 in which is press fitted an elongated cylindrical tube 24 which extends substantially interiorly of the tank 2. Surrounding tube 24 in concentric relation therewith is a second tube 26, the inner end 28 of which is closed as by pinching, crimping or other suitable means. At its outer end, tube 26 is necked inby swaging or spinning at 30 into tight engagement with the outer periphery of tube 24 and brazed to face 29 of the threaded portion 12 of fitting 14. To obtain the desired acoustical properties with minimum restriction of air flow from the compressor, outer tube 26 is provided with two series of slots 32 and 34, respectively. Slots 32 and 34 are indexed with respect to each other and extend substantially halfway around the circumference of the tube. In a typical example a minimum clearance of .020 inch between the inner and outer tubes and a slot width of approximately .030 inch was found to produce the desired reduction in tank resonance without appreciable loss of the compressor output.

in accordance with another feature of the invention, fitting 14 includes a branch arm 36 having an auxiliary inlet opening 38 formed therein which communicates with bore 16. Threadably disposed in opening 38 is a conventional tire type valve 40. Valve 40 allows initial charging of the suspension system by means of conventional tire inflating equipment and thus eliminates the necessity for operation of the vehicle engine to obtain the initial charge.

While but one embodiment of the invention has been shown and described, it will be apparent that numerous changes and modifications may be made therein. It is, therefore, to be understood that it is not intended to limit the invention to the embodiment shown, but only by the scope of the claims which follow.

I claim:

1. A surge muflier for a compressed air storage tank comprising an air inlet fitting detachably secured to said tank, an open ended tubular member connected at one end to said fitting, said tubular member having an imperforate cylindrical wall, a second tubular member disposed in concentric surrounding relation with said first tubular member, one end of said member being closed and the other end being of reduced diameter tightly engaging said first tubular member adjacent said fitting, and outlet means spaced along the periphery of said outer tubular member between the ends of said inner tubular member providing communication with said tank.

2. In combination, a compressed air container, an inlet fitting threadably connected in a wall of said container, an elongated open ended tube secured at one end to said fitting and extending substantially interiorly of said container, said tube having an imperforate cylindrical wall, a cylindrical sleeve surrounding said tube and secured thereto adjacent said fitting, said sleeve being of substantially greater diameter than said tube to provide an annular air space therebetween, means closing the free end of said sleeve, and means forming a plurality of spaced openings along the length of said sleeve, all of which are located between the ends of said tube, said openings permitting discharge of air from said tube into said container.

3. A surge muflier assembly for installation in the inlet port of a compressed air storage tank, said assembly comprising a fitting having an opening extending therethrough, a pair of radially spaced concentric tubes connected to said fitting, one of said tubes communicating with said opening, said one tube having an imperforate cylindrical wall and an open free end, the other of said tubes having one end surroundingly embracing said first mentioned tube adjacent said fitting, means closing the other end of said other tube, and means forming a plurality of slots in said last mentioned tube along that portionof its length radially adjacent said one tube permitting discharge of air from said first tube into said tank.

4. A surge mufller assembly for installation in the inlet port of a compressed air storage tank, said assembly comprising a fitting having an opening extending therethrough, a pair of concentric tubes connected to said fitting, one of said tubes being press fitted in said opening, the other of said tubes having a necked-in end portion surroundingly embracing said first mentioned tube adjacent said fitting, means closing the other end of said other tube, and means forming a plurality of slots in said last mentioned tube permitting discharge of air from said first tube into said tank, said slots being arranged in two groups, the slots in each group extending substantially through half the circumference of said tube, one group being indexed circumferentially 180 relative to the other group.

5. In a device of the class described, a surge mufller comprising an inner open ended tubular member having an imperforate cylindrical wall, an outer cylindrical member having one end thereof closed, said outer cylindrical member being larger in diameter than said inner member and having a necked-in open end surroundingly engaging one end of said inner tubular member to form an air tight seal therebetween, an outlet means spaced along the portion of the periphery of said outer tubular member overlying said inner tubular member.

6. In a device of the class described, a surge muffler comprising a first tube having an open inlet end and an open discharge end with the cylindrical wall thereof being imperforate, a second tube radially spaced from and surrounding said first tube, said second tube having a closed end and being of substantially greater length than said first tube, means forming a necked-in portion on said second tube adjacent the inlet end of said first tube, and a plurality of circumferential slots formed in said second tube, said slots being arranged in two groups axially spaced between the inlet and the discharge end of said first tube, said groups being indexed 180 circumferentially of said second tube.

References Cited in the file of this patent UNITED STATES PATENTS 1,128,306 Goelzer Feb. 16, 1915 1,938,036 Martin et a1 Dec. 5, 1933 2,185,796 McInnis et a1 Jan. 2, 1940 2,483,007 Higham Sept. 27, 1949 2,602,465 Goehring July 8, 1952 2,735,504 Moyer Feb. 21, 1956 2,806,548 Carroll 2. Sept. 17, 1957 

